Gusset plate connections under monotonic and cyclic loading

Walbridge et al. 985
Fig. 2. Gusset plate connection model for Rabinovitch and
Cheng (1993) specimens.
Fig. 3. Linear elastic mesh refinement study: (a) mesh 1 – 206
elements, (b) mesh 2 – 336 elements, (c) mesh 3 – 454 elements,
and (d) mesh 4 – 596 elements.
typical A490 bolt. This value was determined to be
253 kN/mm.
Results
The effect of strain hardening on the load versus displacement
behaviour in monotonic tension was an increase in the
ultimate tensile capacity (Fig. 5). It was found, however, that
the elasto-plastic material model resulted in a better prediction
of the test specimen behaviour. The reasons that the
models with strain hardening tended to overestimate the ultimate
load are believed to be twofold. Firstly, bolt holes were
not incorporated in the gusset plate model. The resulting excess
material along the yield surface of the gusset plate (assuming
a block shear failure mode) is believed to explain to
a large extent the difference between the test results and the
predictions of the gusset plate model with strain hardening.
Another possible explanation is that no attempt was made to
model local phenomena affecting the gusset plate behaviour
near the bolt holes, such as the tearing observed in some of
the tests (Rabinovitch and Cheng 1993). As the goal at this
stage was to accurately predict the observed load versus displacement
behaviour of the gusset plate with a model suit-
Fig. 4. Finite element model of gusset plate with flexible framing
members.
Fig. 5. Effect of material model and boundary conditions on
monotonic tension behaviour for Rabinovitch and Cheng (1993)
specimen A2.
able for application in large parametric studies such as the
one presented herein, it was decided to retain the simplified
idealization of the gusset plate along with the elasto-plastic
material model for the remainder of the study.
As shown in Fig. 5, the effect of incorporating realistic,
flexible boundary conditions (as opposed to rigid boundary
conditions) was a slight reduction in the stiffness of the gusset
plate in the elastic range and a decrease in the ultimate
tensile capacity. The use of an elastic fastener model did not
significantly affect the predicted load versus displacement
behaviour and had little effect on the ultimate load. The
rigid bolt model and flexible boundary conditions were
therefore used in subsequent analyses.
Table 3 summarizes the predicted and actual tensile capacities
for the test specimens of Rabinovitch and Cheng
(1993), attained with finite element models that incorporated
the elasto-plastic material model, the flexible boundary conditions,
and the rigid bolt model. Good agreement between
the test results and the predicted capacity can be seen in this
table, with test-to-predicted ratios varying from 0.93 to 1.08.
© 2005 NRC Canada